The biological response to tissue injury in higher organisms falls into two main categories: wound repair and regeneration (1). In amphibians, the form of wound healing seen is often epimorphic regeneration, where entire limbs can be reformed after amputation (1). In adult mammals, wound healing can involve wound repair or tissue regeneration, including the replacement of mature cells through cell proliferation (7) or replenishment of cells, but not organs, from immature stem cells (9, 11, 25). Complete wound healing, however, with perfect replacement of tissue and function, is typically not observed. Injuries to the central and peripheral nervous system, including optic nerve and spinal cord injuries, are especially refractory to healing. Thus, there is a need in the art for methods and compositions for enhancing wound healing in mammals.